(1/25)^x-26(1/5)^x+25<=0

сделаем замену y=(1/5)^xy^2-26y+25<=0решим уравнение y^2-26y+25=0D=26^2-4*25=576, √D=24y1=1 и y2=25ответ для нераенства с y1<=y<=251<=(1/5)^x<=25ln1<=ln(1/5)^x<=ln25ln1<=x*ln(1/5)<=2*ln5ln1<=x*ln5^-1<=2*ln5ln1<=-x*ln5<=2*ln5-ln1/ln5>=x>=-2*ln5/ln5-log₅1>=x>=-2-2<=x<=-log₅1